Fuel injection spark plug



Sept. 9, 1941. F. J. WIEGAND FUEL INJECTION SPARK PLUG Filed Feb. 28,1940 2 Sheets-Sheet l FIG. 2

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lNyENToR Francw J Meg and.

ATTORNEY Sept. .9, 1941. F. J. WIEGAND FUEL INJECTION SPARK PLUG FiledFeb. 28, 1940 2 Sheets-Sheet 2 INVENTOR Ill/1 WWW m g mam Franc is (IWzLegand.

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i Q 5/ Z?) ATTORNEY Patented Sept. 9, 1941 2,255,203 FUEL INJECTIONSPARK PLUG Francis J. Wiegand, Ridgewood, N. 1., as'signor to WrightAeronautical Corporation, a corporation of New York Application February28, 1940 Serial No. 321,157

' 11 Claims.

This invention relates to internal combustion engines arranged for fuelinjection and in particular, comprises improvements whereby the con.-ventional spark plug of the engine incorporates a fuel injection nozzlewhich heretofore has been a separate device.

By the coordination of the spark plug and fuel injection nomle in asingle unit various advantages accrue, such as:

(a) The cylinder head need have only a single opening for thecombineddevice where before separate openings for the spark plug and theinjection nozzle are necessary. Thus, weakening of the cylinder head dueto the multiplicity of holes is minimized;

(b) The flow of liquid fuel through the injection nozzle has the effectof cooling the spark lug; p. (c) The transfer of heat from the sparkplug to the fuel prepares the fuel for quicker vaporization whenadmitted to the cylinder, particularly when the fuel has low volatility;

(d) The weight of the engine may be reduced, which factor isparticularly important in aircraft engines;

(e) Erosion of the'sparking points should be reduced due to their loweroperating temperatures, and

(1) When two of the combined devices are used in each cylinder, two fuelnozzles as well as two spark plugs would be available an operatingcharacteristics of the engine may be improved by cutting out one of theinjection nozzles at idling speeds while using both spark plugs forignition. When using both nozzles for full power operation improved fueldistribution'would obtain.

The objects of the invention will be apparent from the above remarks andfrom the annexed detailed description of the combined spark plug andfuel nozzle device in connection" with the drawings, in which:

Figs. 1 to 4 are sections through alternate forms of the .devices, and

Fig. 5 is a section on the line 55 of Fig. 4.

In the several figures there arecertain common elements which bear thesame symbols. Referring first to Fig. 1, which shows an elementary inwhich is formed an insulating sleeve 20 locked against displacement by ashoulder 2|. The sleeve 20 and other insulating parts shown in this andother embodiments preferably are formed from a suitable ceramic compoundwhich may be molded into its proper form and which will have adequatemechanical strength and insulating and refractory properties. Thecompound used should also be capable of formation to close dimensionsand have a high finish. Appropriate compounds of this character maycomprise oxides or silicates of certain metals such as tin, aluminum orzirconiur'n, but the invention is not to be construed as beingrestricted to any particular refractory insulating material.

Within the sleeve 20 a metallic electrode sleeve 22 is fitted, suchsleeve terminating at its lower end in an annular sparking point 23 inproper clearance relation to the electrode II. The upper end of thesleeve 22 is spun over an inner insulating sleeve 24, as at 25, toconstitute an electric connecting terminal. The sleeve 24 has fittedadaptation of the invention, the cylinder head is ing l4 against apacking washer Hi. The shell II has an annular or multi point spark plugelectrode ll set into its lower end and the top end i threaded as at I8to receive an upper shell 19 thereto a valve housing 26 terminating atits lower end in a valve seat 21 engageable by the head 28 of a valvewhose stem is indicated at 29. The stem is provided with triangulatedbosses 30 whose apices bear on the interior wall of the sleeve 21 forguiding the valve, and whose depressions permit of the passage of fuelfrom the upper part of the housing 26 to the valve head 28. The housing26 is provided with a shoulder 3| upon which the spring 32 rests, theupper end of the spring engaging adjustable nuts 33 whereby thevalve isnormally held in a closed position. A suitable closure structure for theupper end of the plug assembly is provided whereby fuel may be fed tothe interior of the housing 26 and whereby electrical impulses may beconducted to the sleeve 22. Such a closure structure would be similar tothat shortly to be describedin connection with Fig. 2. It will be notedthat the shell I9 embraces the whole plug assembly and comprises agrounded electrical shield therefor.

In Fig. 2 a shell 36 is screwed into the spark plug bushing I4 andcarries at its lower end the sparking ring H, the shell having a taperedsur face 31 against which an insulating sleeve 38 abuts in sealingrelation, said sleeve extending upwardly and downwardly from the surface31 to embrace a valve housing 38 screwed into the lower end of thesleeve. The valve housing at its lower end comprises an annular sparkingelectrode 40 and comprises thereat the valve seat 21 against which thevalve head 28 may rest. The other elements of the valve assembly aresimilar to that above described. An upper shell 42 is screwed into theshell 36 and is tightened the element 48 is at ground potential. Theelements 4! and 48 are secured to one another by the insulating material49 during the fabrication process- After the assembly is screwed uponthe housing 39, a union nut 50 is assembled thereover and is screwed tothe shell 42. Prior to attachment of the assembly 45 an insulatingannulus 5| is placed thereover to provide further protection againstflashover between the valve housing and shell assembly. The nut 50 isprovided with a protuberance 53 to which an insulated ignition wire 54is led, said wire passing through a hole in the insulating ring 5| sothat the wire thereof may be engaged in a slot 55 in i the element 41.The ignition wire 54 carries conventional shielding which is grounded tothe nut 50, which in turn is grounded through the shell 42 and the shell36. In this embodiment all components of the plug are sealed againstfluid leakage and the electrical path is fully insulated from elementsat ground potential. The valve housing forms the inner spark plugelectrode which is at the same potential as the valve.

In Fig. 3 a shell 58 is threaded into the spark plug bushing l4 andcarries at its bottom end an annular spark plug electrode l1, said shellhaving an inclined annular shoulder 59 against whichan insulating sleeve60 rests, said sleeve extending upwardly and downwardly from theshoulder 59 and comprising a valve housing for the valve 28 and its stem29, said insulating material itself including a shoulder for the valvespring 32. Toward the upper end of the sleeve 66, cross drillings 6| areformed which mate with cross drillings 62 in an intermediate shell 63screwed into the shell 58 to hold the sleeve 60 against the shoulder 59.A ring connector 64 embraces the shell 63 for entry of fuel to the crossdrillings 6| and 62 and into the housing 60, 'said ring being clamped inposition by an upper shell 65 screwed on to the upper end of theintermediate shell 63. An insulating bushing 61 seats upon a shoulder inthe upper shell 65 and has a downwardly extending skirt 68 embracing anelectrical connecting spring 69 resting at its lower end upon the top ofthe valve stem and on its upper end on a metallic connecting pin 70molded into the bushing 61. Said latter sleeve is secured to the uppershell 65 by a cover plug H screwed thereto. The cover plug -H- at itsupper end is provided with a normal thread connection for reception of ashielded ignition wire l0. In this arrangement, the electricalconnection to the plug is made at the top thereof after the manner ofthe conventional spark plug, while the fluid feed connection to the ring64 is spaced therefrom by which manifolding of a plurality of plug unitsmay be more readily accomplished. The arrangement of Fig. 3 lends itselfto air cooled engine cylinders, since the fluid feed ring 64 is elevatedfrom the cylinder head II) a distance sufficient to clear cooling fins(not shown) which may be formed thereon.

, In this embodiment the valve and its stem per se form the centerelectrode for the spark plug and the periphery of the valve head 28forms the inner annular sparking point cooperating with the sparkingelement l1. Preferably, the bottom of the assembly is flush so thatsparking of the plug comprises a flashover from the head 28 to the ringH. The arrangement of Fig. 4 is in general similar to that of Fig. 3,except that the fuel feedring 64 is clamped between the lower shell 58and the cylinder surface, the fuel feed cross holes 15 being formed inthe shell 58 and in the portion of the insulating sleeve 66 below theshoulder 59. In this arrangement the insulating sleeve 60 is clampedagainst the shell 58 by an upper shell 16 which carries the bushing 61,the connector"! and the cover plug II, electrical connection between theelement 10 and the top of the valve stem being accomplished as before bya spring'69. In this arrangement, as in Fig. 3, the valve head 28 andthe ring I! comprise the sparking electrodes, the spark flashing. overthe end of the insulating sleeve 60' which comprises the valve housing.This arrangement would be well adapted for fluid cooled engines wherethe fuel feed ring 64 may conveniently lie adjacent the cylinder headsurface.

Some of the more modern ceramic materials adapt themselves nicely toconstructions of plug 'units herein shown, for they are possessed ofgreat density, smoothness and strength along with excellent insulatingand refractory properties. It is known that highly finished valve seatsmay be formed thereon which allows of the constructions shown in Figs. 3and 4. Incidentally, in the arrangement of Figs. 3 and 4, as in theother arrangements, flashover distances within the plug unit are alladequate to avoid electrical breakdown in operation, and secure sealsagainst fluid leakage are incorporated throughout.

In the use of plugs of this character it will be seen that theintermittent flow of fuel through th plug will afford cooling therefor,while the heat interchange from the plug to the fuel will promotevaporization of the latter. The arrangement of the valve 28 and itsassociated parts is' adapted for use with an external fuel feed pump,metering device and distributor, all of which units are known in theart, so that the valve 28 merely functions as an admission nozzle.Ordinarily, the closing force on the valve 28 is quite large, so thatfuel pressure within the plug proper and upstream of the valve willalways be at a value of several hundred pounds per square inch at whichtemperature gasification of fuels having high'volatility will not belikely to occur at the operating temperatures to which the plug unit issubject.

While I have described my invention in detail in its present preferredembodiment, it will be obvious to those skilled in the art, afterunderstanding my invention, that various changes and modifications maybe made therein without departing from the spirit or scope thereof. Iaim in the appended claims to cover all such modifications and changes.

I claim as my invention:

1.-A combined spark plug and injection valve device for enginescomprising an outer shell adapted to be secured to an engine cylinderand constituting a grounded electrode, a refractory insulating sleevetherein, including a valve seat at its inner end, a valve engageablewith said seat and constituting an inner electrode, said valve includinga spring-loaded stem extending into said sleeve, means to feed liquidfuel to the sleeve hollow, and electrical conducting means contactingsaid valve stem.

2. A combined spark plug and injection valve device for enginescomprising an outer shell adapted to be secured to an engine cylinderand constituting a grounded electrode, a refractory insulating sleevetherein, including a valve seat at its inner end, a valve engageablewith said seat and constituting an inner electrode, said valve includinga spring-loaded stem extending into said sleeve, means to feed liquidfuel to the sleeve hollow, electrical conducting means contacting saidvalve stem, and a grounded electrical shielding casing embracing theentire device.

3. A combined spark plug and injection valve device for enginescomprising an outer shell adapted to be secured to an engine cylinderand constituting a grounded electrode, a concentric refractoryinsulating sleeve therein comprising at one end an integral valve seat,the sleeve fitting closely into said shell, a liquid fuel feedconnection secured to the device for feeding fuel to the sleeve hollow,a valve comprising a stem in the sleev hollow and a head engageable withsaid valve seat, and an electrical connection to said valve.

4. A combined spark plug and injection valve device for enginescomprising an outer shell adapted to be secured to an engine cylinderand constituting a grounded electrode, a concentric refractoryinsulating sleeve therein comprising at one end an integral valve seat,the sleeve litting closely into said shell, a liquid fuel feedconnection secured to the device for feeding fuel to the sleeve hollow,a valve comprising a stem in the sleeve hollow and a. head engageablewith said valve seat, an electrical connection to said valve, a centralvalve and seat assembly in insulated relation to said shell andcomprising a center spark plug electrode, the valve including a springnormally holding same closed, and a pressure fuel feed connection tosaid valve and seat assembly.

5. A combined spark plug and injection valve device for enginescomprising an outer shell adapted to be secured to an engine cylinderand constituting a grounded electrode, a concentric sleeve thereincomprising a valve seat and a refractory insulator, the sleeve fittingclosely into said shell, a liquid fuel feed connection secured to thedevice for feeding fuel to the sleeve hollow, a valve comprising a stemin the sleeve hollow and a head engageable withv said valve seat, anelectrical connection to said valve, a central valve and seat assemblyhaving an external flange and in insulated relation to the shell andcomprising a center spark plug electrode, a nut embracing the assemblyin insulated relation thereto securing the assembly to the shell, a fuelconnection passing intothe assembly, and a cover element securing theassembly against leakage and comprising an insulated electricalconnection to said assembly.

6. A combined spark plug and injection valve device for enginescomprising an outer shell adapted to be secured to an engine cylinderand constituting a grounded electrode, a concentric sleeve thereincomprising a valve seat and a refractory insulator, the sleeve fittingclosely into said shell, a liquid fuel feed connection secured to thedevice for feeding fuel to the sleeve hollow,

a valve comprising a stem in the sleeve hollow and a head engageablewith said valve seat, an electrical connection to said valve, a centralvalve and seat assembly having an external flange and in insulatedrelation to the shell and comprising a center spark plug electrode,a nutembracing the assembly in insulated relation thereto securing theassembly to the shell, a fuel connection passing into the assembly, anda cover element securing the assembly against leakage and comprising aninsulated electrical connection to said assembly, said shell, nut andcover comprising a shielding completely embracing the device.

7. In a spark plug and valve device,a shell a refractory insulatingsleeve therein, the sleeve bottombeing substantiallyiiushwith the shellbottom and comprising a valve seat, means to secure the sleeve withinthe shell, a valve comprising a head engageable with the sleeve seat anda stem piloted in the sleeve, a spring between the stem and sleeveurging the valve closed, a fuel feed ring embracing the shell, thelatter and the sleeve having registering cross holes admitting fuel tothe sleeve interior, a fuel tight insulating closure for the sleeveinterior, and an electrical conductor passing therethrough electricallyconnected to said valve stem; said valve and shell respectivelycomprising center and edge spark plug electrodes.

8. In a spark plug and valve device, a shell, a refractory insulatingsleeve therein, the sleeve bottom being substantially flush with theshell bottom and comprising a valve seat, means to secure the sleevewithin the shell, a valve comprising a head engageable with the sleeveseat and a stem piloted in the sleeve, aspring between the stem andsleeve urging the valve closed, a fuel feed ring embracing the shell,the latter and the sleeve having registering cross holes admitting fuelto the sleeve interior, a fuel tight insulating closure for the sleeveinterior, an electrical conductor passing therethrough electricallyconnected to said valve stem; said valve and shell respectivelycomprising center and edge spark plug electrodes, and a metallic coverembracing said insulating closure, secured to the shell and comprisinggrounded electrical shielding for the device.

9. A combined spark plug and injection valve device comprising an outershell for securement to an engine, a homogeneous refractory insulatingsleeve fixed therein having its end face formed as a valve seat, anaxially movable valve stem passing through the sleeve having a headengaging said seat, and said shell and head comprising spark plugelectrodes.

10. A combined spark plug and injection valve device comprising an outershell for securement to an engine, a homogeneous refractory.insulatingsleeve fixed therein having its end face formed as a valve seat, anaxially movable valve stem passing through the sleeve having a headengaging said seat, said shell and head comprising spark plugelectrodes, means for forming an electrical connection to said valvestem, and means to feed fuel to the sleeve hollow.

11. In a combined spark plug and injection

